The History Of Solar Energy

Boffins will tell you that all energy comes from the sun, including fossil fuels. Over millions of years, photosynthesizing trees, plants and other species transformed atmospheric molecules into higher energy states which humans then burn as oil, coal, and gas.

But what about actual solar energy panels that convert sunlight into electricity directly? Well, that’s a far more recent phenomenon, made possible by the photoelectric effect. The idea is to take a semiconductor, like silicon, and then use the special properties of the material to convert photos (sunlight) into electrons that flow in a circuit.

The physics behind this process is complex (and it took until the 19th century for scientists to figure it out). But, if solar energy succeeds in replacing fossil fuels in the future, it could be one of the most important discoveries in history.

The use of solar energy began in the ancient world with the invention of glassmaking. Europeans found they could blow glass in a way that could collect light from a large area and concentrate it into a smaller one to start fires.

During the second century, B.C., the Greek mathematician Archimedes used this principle to defend the city of Syracuse from invasion. Under his instructions, soldiers turned their bronze shields to a specific angle to set incoming Roman ships ablaze.

Numerous other direct solar energy use instances are also evident in the ancient world. For example, the ancient Chinese manufactured “burning mirrors” for religious reasons while the Byzantines added sunrooms to houses using reflective metal.

However, these applications were crude by modern scientific standards and didn’t involve electricity. Essentially, technologies concentrated or reflected heat to raise temperatures in the vicinity.

During the scientific revolution in Western countries, things changed. Scientists began probing the nature of the photoelectric effect – or more accurately, the photovoltaic effect – to determine whether it was possible to convert sunlight (one form of energy) into electricity (another form of energy).

As with many scientific endeavors, progress was haphazard. Initially, 19th-century researchers like Robert Sterling sought to advance pre-existing solar collector technology, transforming the sun’s thermal energy into usable work. Lord Kelvin demonstrated a similar system that added a dish to Stirling’s system and presented it in his university lecture classes.

This discovery led inventors to wonder whether such effects could work on the nascent technology of the time, like railways. French mathematician August Mouchet developed the idea of a solar-powered steam engine that would collect solar energy from a reflective bucket at the front to heat water in a tank, eliminating the need for coal.

However, it wasn’t until French scientist Edmond Becquerel discovered the photovoltaic effect in 1839 while experimenting with electrolytic cells that modern solar panels became a theoretical possibility. He showed that cells comprising two metal electrodes placed in an electricity-conducting solution could produce more electricity when exposed to light. The significance of the breakthrough wasn’t immediately apparent, but it hinted at deeper, yet-to-be-understood physical laws in a world dominated by the Newtonian paradigm.

Thirty years later, Willoughby Smith built on this discovery by observing the photoconductivity of selenium. The breakthrough showed that the metal’s electrical resistance changed depending on the amount of light falling on it, setting the basis for converting images into electrical signals, photoelectric cells, and even television. Then, in 1883, American inventor Charles Fritts introduced the concept of the first solar cells made from selenium wafers. He believed the metal could generate sufficient efficiency to complete a circuit, though creating a working prototype was challenging.

The scientific breakthrough that would make semiconductors feasible arrived when Albert Einstein published a paper on the photoelectric effect in 1905. He proposed that light is made of tiny quanta called photons and that each carries energy proportional to the frequency of the light wave. This insight permitted an explanation of the photoelectric effect – the prior observation that metal ejects electrons when it comes into contact with light. Later, researchers like Robert Millikan provided experimental proof of the photoelectric effect, encouraging more research and investigation.

However, the pieces weren’t quite in place to create today’s photovoltaic solar panels. That still required a materials science breakthrough. The first step in this journey came when Polish scientist Jan Czochralski found a way to grow single-crystal silicon. He saw that he could melt and then freeze the compound into a crystalline state, allowing engineers to benefit from its advanced properties. At the same time, William J. Bailey of the Carnegie Steel Company invented a crude solar collector using copper coils inside an insulated box. It couldn’t function as a modern device but provided the backdrop for later design developments.

The pieces finally came together in 1953 at Bell Labs when researchers and scientists Gerald Pearson, Calvin Fuller, and Daryl Chapin developed the first photovoltaic cell capable of powering everyday equipment using light from the sun. The first panel had an efficiency of 4%, growing to over 11% within the decade.

Following the discovery and subsequent publicity, interest in solar photovoltaic technology exploded. Western Electric began selling licenses for the technology, permitting the first hand-held, motorized equipment that didn’t require batteries or a diesel generator. Office buildings also began to benefit from solar panel technology. For example, engineers fitted the energy-generated devices to the Bridgers-Paxton Building in Albuquerque, New Mexico in the 1950s.

In 1963 Japan installed the world’s largest solar array on a lighthouse, generating over 242 watts when in use, enough to power the installation’s massive bulb. Later, NASA launched its Orbiting Astronomical Observatory in 1966, which had a huge 1-kW photo-array. Other firsts include Paul MacCready’s solar-powered aircraft in 1981 and the first megawatt-scale solar power plant developed by ARCO Solar in Hesperia, CA, in 1982.

Later, solar panel technology began to emerge as a significant source of energy in places like Washington State. For example, Seattle built the Bullitt Center, one of the world’s greenest office buildings. Since 2018, the city’s use of solar power has more than doubled.

Looking ahead, solar panel technology seems like the most likely candidate to facilitate the energy transition and net zero. Solar energy is abundant and will continue hitting the Earth for millions of years.